The present invention relates generally to data distribution systems, and more particularly, to improved methods and apparatus for providing Internet cache content delivery using a data distribution system.
The assignee of the present invention has developed a data distribution system, and in particular, a satellite-based data distribution system, that is used to distribute data supplied by content providers to personal computers of clients. In order to allow clients to have improved response times to obtain data distributed by the data distribution system, an important aspect of the system was developed relating to caching services that addresses this need.
Several companies, including Inktomi, Cache Flow, and NetWork Appliance, for example, currently make cache appliances or specific software which are targeted at Internet service providers. SkyCache is currently operating caching services using satellite communications.
It would be an improvement to have a method and apparatus that provides Internet cache content delivery using a data distribution system.
The present invention provides for a cache system and caching method that is used to improve data delivery service provided by a data distribution system, such as a satellite-based data distribution system. The present invention uses a master cache in which predictive harvesting of content is performed based upon probability distributions of individual caches satisfying requests from their users (clients). Content in the master cache is distributed to user sites by way of the satellite-based data distribution system, and local caches at user sites are automatically loaded with incoming content. The use of the satellite-based data distribution system provides an efficient economic multiplier.
More specifically, an exemplary system comprises a master cache that receives content for distribution by the data distribution system to one or more users. A gateway receives content distributed by the data distribution system from the master cache. One or more local caches store the content received by the gateway destined for the one or more users. Harvesting software processes information from the master cache and the gateway that corresponds to probability distributions that the local caches satisfy requests from their respective users to predictively distribute the desired content to the respective users.
Content distributed by the data distribution system to the gateway is transferred into the local cache by creating a pseudo client on the gateway, receiving an interrupt at the pseudo client indicating that that content has arrived at the gateway, enabling the gateway as a sibling cache for the local cache, requesting content to be transferred from the sibling cache to the local cache, verifying that content has been transferred to the local cache during the transfer process, and disabling the gateway as a sibling cache of the local cache at the completion of the process. The local cache retrieved the content from the sibling cache until all content has been transferred.
The master cache is built by processing statistics derived from the master cache and the local cache to produces a list of content to add to the master cache and a list of content to delete from the master cache. A pseudo client is formed that retrieves and verifies the content to be added to the master cache. The verified content is then transmitted from the master cache to the local cache.
Caching is used to improve the response time of a user (client) that is served by the cache system employed in the data distribution system. Caching also benefits service providers by reducing communications costs between the service environment and the external world. Using satellite transmission services allows cost savings and response times to be further enhanced for a large number of service providers by allowing aggregation of their individual requests.
The use of the satellite-based data distribution system provides for efficient distribution of cache content over a wide geographical area thereby allows many user sites to simultaneously update their local caches. This reduces cost of terrestrial infrastructure for the individual user sites.